Variable speed gear



Sept. 10, 1929. s. RUSHFIRTH VARIABLE SPEED GEAR 2 Sheets-Sheet 1 Filed Nov. 10, 1927 q A. /u .I:

Sept. 10, 1929. s. RUSHFIRTH VARIABLE SPEED GEAR Filed Nov. 10, 1927 2 Sheets-Sheet 2 Patented Sept. 10, 1929.

UNITED STATES SAVILLE RUSHFIRTH, 013 ST. ANNES-ON-SEA, ENGLAND.

VARIABLE SPEED GEAR.

Application filed November 10, 1927, Serial No. 232,411, and in Great Britain November 17, 1926.

This invention relates to variable speed gears and in particular to gears of the kind embodying a part having an epicyclic motion the control of which provides the required alternative ratios. y

The object of this invention is a gear of the above kind having an improved construction and arrangement of parts. I

According to the invention the gear comprises a housing, two adjacent co-axial shafts mounted in the housing, a pinion wheel on each of the adjacent ends of the shafts, the two pinion wheels being of different diameters, a frame or casing journaled on the shafts, at least one compound pinion Wheel mounted in the frame or casing to engage with the two different sized pinion wheels aforesaid, a clutchmember slidably mounted on the frame or casing, alternative complementary clutch members for the sliding clutch member, one mounted on one of the shafts and the other secured to the housing, means for sliding the clutchmember and a spring betweenthe sliding clutch member and its frame or casing to cause it to engage normally with its complementary clutch 'member on the one shaft.

Such combination of parts constitutes a single gear unit and according to further features of the invention a variable gear may consist of two or more of such units in combination and additional ratios and a reverse ratio may be embodied in a gear unit.

The accompanying drawingillustrates one example of the improved variable speed gear consisting of two different gear units in cornbination, in which:

Fig. 1 is a sectional plan on line 1--1, Fig. 2.

Fig. 2 is a sectional elevation of the left hand gear unit on line 22,Fig. 1.

Fig. 3 is a sectional elevation of the right hand gear unit on line 33, Fig. 1.

Fig. 4 is a diagram illustrative of the reverse ratio mechanism, embodied in the right hand gear unit.

Fig. 5 is a diagram of the parts embodied in the right hand gear unit to give the third.

forward ratio.

Fig. 6 is a part sectional side elevation of the gear operating mechanism and a side exterlor elevation of the gear housing (taken on line 6-6 Fig. 1). p

Fig. 7 is a side exteriorview, partly in sectlon, of a single gear unit arranged for use between the engine and the usual change speed gear, or Cardan shaft, of an automobile- I As shown in Fig. 1, the variable gear consists of a housing a provided with suitable lugs a for attachment to the chassis of an automobile, and having two compartments a and a each of which is adapted to contain a variable gear unit. In the ends of thehousing and in the centre partition 6 between the two compartments are ball bearing housings I), b and Z2 inwhich are journaled shafts 0 c and 0 arranged co-axially and end to end. The outer ends of the shafts c and c are each provided with a spider d, d respectively, for a flexible coupling'of known construction.

The first gear unit in the compartment a consists of a shelllike clutch member 6 secured to a flange 6 on the shaft c ,"the clutch member having a detachable sleeve or collar 6 with cone shaped clutch facing e such collar being secured to the clutch member after assembly of the other parts of the. unit. On the end of the shaft 0 within the compartmenta is secured a pinion wheel f, overhanging the end of the shaft 0 which is turned down, the wheel being bushed to form a supporting'bearing thereon for the ends of the shafts. Opposite andadj acent'to the pinion wheel f is a smaller pinion wheel secured on the shaft 0 Journaled on ball races 9, 9 carried on the pinions f, f is a casing g with its cover 9 in which is mounted a compound pinion h on a spindle 7L and having toothed parts gearing with the two pinions f and P. In the casing isa balance weight k opposite the pinion h, and spaced equally'around the casing are spring tubes secured by screws j andserving to fasten the cover g of the cas g, 9 ingg is splined, see Fig. 2, and on it is slidably mounted a clutch member having a disc like part 70 the member 7a havinga conical clutch face is? and the'part 76 having a clutch face 10 In the .part is arelocating The outer circumference of thecaspins m for springs m provided in the spring tubes 7', and behind the part k is an operating fork the arms of which are provided at their extremities with anti-friction rollers m to engage with the outer face of the part 70 In the compartment a is a stationary bracket n carrying a friction face n for the engagement of the clutch face k of the part k of the sliding clutch member.

The variable gear unit in the compartment (1 comprises many parts similar to these in the other unit, the principal differences of construction being as follows. The shaft 0 is made hollow from its inner end, the extreine inner end being bushed to fit over the spigot on theend of the shaft 0 A sliding pinion wheel 0 is provided on the inner end of the shaft 0 in place of the pinion wheel f, sliding on splines on the end of the shaft and connected to a dumb-bell shaped'operating rod 10 within the shaft by a pin 1 passing through slots 32? in the shaft. T e journal b is made long enough to'accoinmodate an operatingflangep on the shaft connected to the other end of the operating rod 29 by a pin 39* passing through slots 39 Also the compound pinion h is made longer leaving a space between the two toothed ends, and a reverse pinion g is mounted in the'casing 9 such pinion meshing with one end of the pinion it and having a toothed portion positioned between the two toothed portions of the pinion h and adapted to be engaged by the sliding pinion wheel 0. In Fig. 4 the dotted positionof the pinion 0 shows the position for obtaining the reverse ratio.

In Fig.5 is shown an arrangement wherein the reverse pinion g is shown dotted behind the pinion i which is also provided with an be built direct on to the'fiy wheel 6 of an engine for an automobile, an anti-friction thrust race member u beingprovided on the outer end of the shaft for operating the sli'd ing clutchmemb'er.

In operation, with the engine, running and the sliding clutch member of the left. hand gear unit in the neutral positioni. e. with neither of the clutch faces in engagement, the

' casing g revolves freely while the shaft 0? remains stationary.- Low gear is engaged by operating the clutch mechanism to bring the clutch faces is? and n into engagement thereby checking rotation of the casing 9 The 'wheel 0 being in the position shown.

viously by combining the ratios thus obtained three different speed ratios may be obtained,

or four if the two lower ratios are different. Reverse is obtained from the second gear unit by sliding the pinion 0 into engagement with the pinion g and using the clutch operating mechanism as for low gear. When a double, oritwo unit gear is employed two ratios of reverse are available as well as the one forward, and also where an extra ratio is added to either unit the extra ratios available from the gear as a whole will be increased by the number of ratios in the other unit.

The chief advantages of the gear are in its simplicity'of construction and use, absolute silence when on top ratio when it runs without wear in'the other parts of the unit provided for giving the lower ratio, the gear unit turning as a whole. The parts are easy to produce and to balance, overhanging shafts and side loads are avoided as far as possible and the gear is'designedfor efficient service generally.

The gear maybe used separately or in conjunction with an'existing gear box to provide other ratios and easy changing'for at least one of such ratios. What I claim is a 1. A variable speed gear comprising two shafts, a housing rotatably mounted over the ends of the shafts, gearing on the ends of the shafts, differential gearing within the housing with alternative ratios engaging the gearing on the shafts, selector operating mechanism for the gearing, a stationary member adjacent to the housing, a clutch part on said stationary member, a cup-shaped clutch part overhanging said housing and a compound clutch member slidably keyed on said housing having a coacting clutch sure,

face extending into said cup-shaped clutch part to engage the same, and a coacting clutch surface to engage alternatively with the clutch part of said stationary member, as

set forth.

2. A variable speed gear comprising two shafts, a housing rotatably mounted over the ends of the shafts, a first pinion gear secured on the end of one shaft within the casing, a second or selector pinion gear slidably mounted on the end of the other shaft within the v casing, differential gearing comprising a compound pinion wheel having toothed portions, one engaging the said first pinion gear and the other adapted to be engaged by the second or selector pinion gear, a reverse pinion mounted in the housing engaging the compound pinion Wheel and presenting an alternative engagement for the selector pinion, selector operating mechanism for sliding the selector pinion gear, a stationary member adjacent to the housing, a clutch part on said stationary member, acupshaped clutch part overhanging said housing and a compound clutch member slidably keyed on said housing having a coacting clutch surface extending into said cup-shaped clutch part to engage the same, and a coacting clutch surface to engage alternatively With the clutch part of said stationary member, as set forth.

In testimony whereof I have signed my name to this specification.

SAVILLE RUSHFIRTH. 

